What is the best over-the-counter cough medicine for a patient, potentially with conditions like asthma or Chronic Obstructive Pulmonary Disease (COPD)?

Best Over-the-Counter Cough Medicine

Dextromethorphan at 60 mg is the most effective over-the-counter cough suppressant for dry, nonproductive cough, with a superior safety profile compared to codeine-based alternatives. 1, 2

First-Line Approach for Acute Dry Cough

• Start with simple home remedies like honey and lemon mixture, which are inexpensive and have evidence of patient-reported benefit 1, 2
• Voluntary cough suppression through central modulation of the cough reflex may be sufficient to reduce cough frequency 1, 2
• Most acute viral cough is self-limiting, lasting 1-3 weeks, and often does not require prescribed medication 3, 1

Recommended Pharmacological Treatment

Dextromethorphan (Preferred Agent)

• Dextromethorphan is the preferred OTC antitussive due to equivalent efficacy to codeine but without drowsiness, nausea, constipation, or physical dependence 1, 2
• Maximum cough suppression occurs at 60 mg doses, with a clear dose-response relationship 1, 4, 2
• Standard OTC doses (15-30 mg) are often subtherapeutic and inadequate for optimal cough suppression 1, 4, 2
• Typical dosing is 10-15 mg three to four times daily, with a maximum daily dose of 120 mg 2
• For severe cough requiring maximum suppression, a single 60 mg dose can be used 2
• Extended-release formulations (like Delsym®) provide 12-hour relief with convenient twice-daily dosing 5

First-Generation Antihistamines (For Nocturnal Cough)

• First-generation sedating antihistamines (e.g., diphenhydramine) can suppress cough and are particularly useful when cough disrupts sleep due to their sedative properties 1, 4, 2
• These are most appropriate for nighttime use when the sedative effect is beneficial 1, 4

Menthol Inhalation (Adjunctive)

• Menthol suppresses the cough reflex when inhaled, providing acute but short-lived relief 1, 2
• Can be prescribed as menthol crystals or proprietary capsules 1
• Useful for quick temporary relief as an adjunct to other treatments 1, 2

Agents NOT Recommended

• Codeine and pholcodine have no greater efficacy than dextromethorphan but have significant adverse side effect profiles including drowsiness, constipation, and physical dependence 1, 4
• Expectorants, mucolytics, and antihistamines (non-sedating) lack consistent evidence for beneficial effects in acute cough 3
• Bronchodilators (like albuterol) are not recommended for acute cough not due to asthma 3
• Over-the-counter combination cold medications (except older antihistamine-decongestant combinations) are not recommended until proven effective in randomized controlled trials 3
• Zinc preparations are not recommended for acute cough due to the common cold 3

Special Considerations for Asthma/COPD Patients

• In patients with asthma or COPD, treat the underlying disease first rather than suppressing cough 1, 2
• Cough suppression should be avoided if cough serves a protective clearance function 1, 2
• Consider temporarily adjusting chronic disease medications (asthma, COPD, cardiac failure, diabetes) during acute respiratory infections 3, 1
• For COPD patients with chronic bronchitis, central cough suppressants like dextromethorphan are recommended for short-term symptomatic relief 3, 4
• Ipratropium bromide (inhaled anticholinergic) is the only inhaled agent recommended for cough suppression in chronic bronchitis or upper respiratory infection 3, 1

Critical Pitfalls to Avoid

• Using subtherapeutic doses of dextromethorphan (less than 60 mg) may provide inadequate relief 1, 2
• Suppressing productive cough in conditions like pneumonia or bronchiectasis where clearance is essential 2
• Not recognizing that some dextromethorphan preparations contain additional ingredients like acetaminophen, which requires caution 1
• Failing to assess for pneumonia in patients with tachycardia, tachypnea, fever, or abnormal chest examination findings before using cough suppressants 1

Red Flags Requiring Immediate Medical Evaluation

• Hemoptysis (blood in cough) 1
• Increasing breathlessness suggesting asthma or anaphylaxis 1
• Fever, malaise, and purulent sputum indicating possible serious lung infection 1
• Tachycardia, tachypnea, or abnormal chest examination findings suggesting pneumonia 1
• Cough persisting beyond 3 weeks requires discontinuation of antitussive therapy and full diagnostic workup 2

Treatment Duration

• Dextromethorphan should be used for short-term symptomatic relief only, typically less than 7 days 4, 2
• If cough persists beyond 8 weeks, consider diagnoses other than postinfectious cough 1, 2